Piezoelectric gas lighter

ABSTRACT

A piezoelectric crystal or element is deformed to produce an electric spark which is employed to ignite a combustible gas. The piezoelectric element is deformed by a movable hammer which is spring-biased toward and arranged to strike the element.

United States Patent 11 1 Lundh Feb. 19, 197 1 PIEZOELECTRIC GAS LIGHTER [56] References Cited [75] Inventor: Stig Valdemar Lundh, Jakobsberg, UNITED STATES PATENTS Sweden 3,408,153 10/1969 lshiguro 431/143 3,449,637 6/1969 Suzuki 1 317/81 [73] Ass'gnee' g y Tgkmk 3,457,461 7/1969 Steinke et al. 317 81 we 3,486,075 12 1969 Steinke et 111...... 317 010. 11 [22] Filed: Dec. 15, 1972 3,521,987 7 1970 G616 431/255 3,540,823 11/1970 Ebine et a1, 431/255 [21] Appi. No.: 315,419

Primary Examiner-Volodymyr Y. Mayewsky [30] Foreign Application Priority Data Dec.23, 1971 Sweden 16575/71 [57] ABSTRACT r l A piezoelectric crystal orelement is deformed to pro- 52 US. c1 317/81, 310/87, 317/DIG. 11, duce an electric sparkwhich is mployed to ignite a 317/96 431/255 combustible gas. The piezoelectric element is de- [51] Ilit. Cl. F2311 3/00 formed by a movable hammer which is springbiased [58] Field of Search. 317/81, 96, DIG. 11; 431/143,

toward and arranged to strike the element.

4 Claims, 4 Drawing Figures PIEZOELECTRIC GAS LIGHTER My invention relates to gas lighters of the kind which employ a piezoelectric crystal or element and manually operable striking mechanism to deform the element to produce an electric spark to ignite a combustible gas.

An object of my invention is to provide a small, well functioning and cheap lighter arrangement for all types of combustible gases. The lighter shall function during very long time without any service, such as reloading or exchange of worn-out parts. It must further be moisture-safe and stand exterior stresses without the vital parts of the lighter being damaged.

The lighting spark is obtained from a piezoelectric element which can be ofa kindknown per se and which is actuated by an impacing mechanism. By pressing a push button, which is so placed at the lighter that this can be done by a finger, a spring-loaded hammer placed inside the push button is loaded and released when the push button is fully pressed in'and makes a stroke on the impact-receiving part of the piezoelectric element. Then the pressure change is received which is required for the element to generate a piezoelectric current sufficient for producing a lighting sparkv over the spark gap of the lighter.

The invention will be described in the following with reference to embodiments shown in the accompanying drawing:

FIG. 1 shows a longitudinal section through the impacting mechanism of the lighter in inactive position and the arrangement of the piezoelectric element in relation to the impacting mechanism;

FIG. 2 shows the same lighter turned 90 about the longitudinal axis and the push button pressed in to the releasing position;

FIG. 3 shows the lighter of FIGS. 1 and 2 embodied in a separate hand lighter unit; and

FIG. 4 is a fragmentary view of parts shown in FIG. 3 illustrating a modification of the invention.

The lighter of FIG. 1 comprises a tubular outer sleeve 1 which contains a piezoelectric element 2, the front impact-receiving end'thereof having a protruding part and being centered in the sleeve I by a shallow washer 3. The shallow shape of the washer 3 makes it possible for the'other end of the piezoelectric element to deviate from the center line as much as the free space between the element and the sleeve without any stress upon the impact-receiving part of the element. The element end rests on a T-shaped bracket 9, which is attached to the sleeve 1 in two rectangular holes la in the sleeve wall. The brakcet 9 is fixed after mounting by riveting or bending of the ends of the transverse part of the bracket which extends outside the sleeve. By the secure attachment of the bracket 9 in the sleeve 1 the mass of the sleeve will act as a recoil suppressor for the bracket of the element. Good electric contact between the two ends of the piezoelectric element and the material is essential, because these form one pole of the element and an insulated conductor 10 the other pole. For

will expand against the inner wall of the sleeve 1 and thereby prevent the inner sleeve 4 from sliding from the element at the stroke. The return spring 6 can therefore be made with a small spring power sufficient to return the push button 8 to the starting position. The push button 8 is prevented from-sliding out of the sleeve 1 by having two different diameters, the larger diameter part forming a guide in the sleeve 1, one end of which is folded inwards to an inner diameter which is somewhat larger than the smaller diameter of the push button.

The embodiment described permits relatively large tolerances of the length of the parts, because differences are compensated by the return spring 6. The push button 8 has a bore in which the striking spring 7 can easily move. At theentrance the bore is conical and at the bottom it has a somewhat smaller diameter than the striking spring 7. The end turn of the spring 7 therefore will stick to the button in the bottom of the bore when the push button is pressed in. The striking spring 7 is arc-shaped so as to make the part of the spring outside the push button deviate from the center line in relation to the inner sleeve 4. The striking hammer 5 is attached to the striking spring by a flange 50' between the head and the shaft of the hammer and has a diameter somewhat larger than the inner diameter of the striking spring. If the shaft of the hammer 5 is pressed into the striking spring 7, the end turn of the spring when it is pressed to the hammer will creep over the said flange and thereby the hammer is prevented from sliding out of the spring.

a In the following, the function of the striking mechanism will be described.

When the push button 8 is pressed in, the striking hammer 5 will slide forward and rest on the front edge of the inner sleeve 4 because the hammer is displaced from the center line by the arcuate shape of the striking spring 7. The piezoelectric element 2, which has been under pressure from the return spring 6 via the inner sleeve 4 and the washer 3, now receives an increased pressure by the spring force from the spring 7 which is compressed with the hammer resting on the sleeve 4. During the compressing movement the hammer will stay resting on the edge of the sleeve 4 since the contact point is displaced in relation-to the center line. When the push button 8 approaches the bottom position, the conical inside part of the button moves the hammer in the direction to the center line. In order to facilitate this displacing movement and decrease wear, the hammer 5 has a conical shape corresponding to the conical part of the button 8. Since it is desirable to have the contact point for keeping the hammer as far as possible from the center, the contact surface of the hammer can be spherical (not shown). When the hammer has been sufficiently displaced, it leaves the edge of the inner sleeve 4 and is thrown by the spring 7 against the impact-receiving part of the element. During the movement of the hammer against'the impact-receiving part the element will be released from part of the spring load and only have the load from the return spring 6. This increases the pressure change in the element at the impact of the hammer. I

Since the catching surfaces are circular, the holding point can move around the edges of the inner sleeve and the hammer by turning the button or by the turning which occurs at the compression of the striking spring 7, which will extend the life of the mechanism. When the conductor 10 is arranged in series with a spark gap,

as shown in FIG. 3 and described hereinafter, a heavy spark is produced at the spark gap when the button 8 is pressed in. When the push button 8 is released the hammer 5 is returned to its initial position shown in FIG. I by the return spring 6. This is due to the fact that the push button 8 is biased to its outer position in FIG. 1 by the return spring 6 which is under compression and between the inner sleeve 4 and push button 8; As explained above, the rear end portion of the striking spring 7 is anchored to the push button 8 and the hammer 5 is movably carried at the forward end of the striking spring 7. The distance between the push button 8 and the hammer 5 is such that, when the push button 8 moves rearward to its outer position, the hammer 5 is bodily carried rearward with the push button 8 to its inactive or initial position shown in FIG. 1.

The hand lighter unit shown in FIG. 3, which embodies the lighter of FIGS. 1 and 2, will be described in the following. It is intended for use with gas operated heating apparatus, such as, for example, welding units, LP- burners and gas stoves. The hand lighter unit in FIG. 3 is shown partly in section to illustrate the conductor 10 and the attachment of the electrode 34 thereto. In the hand lighter unit, the spark-producing means described above and shown in FIGS. 1 and 2 is employed. In FIG. 3, the negative electrode is shaped as a casing 31 having an opening for the conductor 10 bent toward the lighter mechanism and parts abutting the sleeve 1 and electrically connected thereto. The casing is fixed in the longitudinal direction by the bracket 9, which is formed as a loop and has an end with an angular part which is inserted into the rear part of the casing in the rectangular hole. After mounting, the casing is'kept in its place by a sleeve 32 pushed over the casing and the mechanism. To facilitate mounting of the sleeve 32, which is made of some elastic material, the casing is not parallel to the mechanism but is at a somewhat larger distance from the center line of the mechanism at the electrode side than at the bracket 9 side. The front end of the casing 31 is extended and shaped as a'pipe with a larger diameter part forming the lighter head, in which insulation 33 and the electrode 34 are disposed. The conductor 10 is placed in the pipe and extends to the insulation 33, which is in the shape of a pipe and formed by heat-resistant, non-conductive material.

For certain types of gas burners, in which the gas has a high velocity, for instance in welding units, it can be difficult to light the gas without decreasing the gas velocity. For this purpose the lighter head can be changed in the manner shown in FIG. 4. In FIG. 4 the lighter head 35 is extended so that the insulation 33a and the electrode 340 are disposed inside the opening of the lighter head. The spark gap is formed between the electrode 34a situated in the center 'and radially out to 5 d. a member movable in said housing between outer and inner positions, said member including a push button accessible exteriorly of said housing for manually imparting movement thereto from its outer position toward its inner position,

e. striking means comprising a hammer for imparting a hammer blow upon said element means,

. elongated compressible spring means to effect movement of said striking means in a path ofmovement toward said element means, said spring means being compressible from an inactive position to an active position by movement of said member from its outer to its inner position, the rear end portion of said spring means being anchored to said movable member, said striking means being movably carried within said housing at the forward end portion of said spring means,

g. the forward end portion of said spring means being bent to hold said striking means in a position laterally displaced with respect to the center line of said spring means at the rear end portion thereof,

h. a part supported in said housing between said element means and said movable member, said part having a surface portion in the path of movement of said striking means which obstructs movement and provides a support against which said striking means initially rests in its path of movement toward said element means when said spring means is being compressed from its inactive to its active position, and

i. means for moving said striking means at the forward end portion'of said spring means toward the center line of the rear portion of said spring means and out of engagement with said surface portion when said spring means is compressed and in its active position, said striking means upon movement out of engagement with said surface portion being free to move in its path of movement toward said piezoelectric element means to impart a hammer blow thereto to generate a voltage and to spark across said gap,

j. said means for moving said striking means out of engagement with said surface portion comprising a part of said movable member facing said striking means which is shaped to effect such movement of said striking means with movement of said member against said striking means.

2. A push button piezoelectric lighter as set forth in claim 5 in which a. said movable member is axially recessed, said reeess defining a bore extending from the inner end toward the outer push button end of said member,

b. said elongated spring means comprising a helical coil spring, the rear end portion of said coil spring being frictionally held in said bore to anchor said coil spring to said movable member, and

c. said bore at the inner open end thereof being of I conical form and enlarged and providing a surface which defines said part of said movable member facing said striking means,

d. said enlarged open end of said bore, with movement of said member against said striking means, clutching the latter to move said striking means out of engagement with said surface portion.

3. A push button piezoelectric lighter as set forth in claim 6 in which a. said striking means comprises a rear plug-shaped part and a front striking head part serving as said hammer,

b. said striking head part being of larger crosssectional area than-said plug-shaped part, and

c. said plug-shaped part extending within the front end portion of said coil spring.

'4. A push button piexoelectric lighter as set forth in claim 5 in which (a) said housing comprises an elongated hollow outer sleeve,

b. said piezoelectric element means being disposed within said housing at one end thereof,

c. said movable member being disposed within said outer sleeve at the opposite end thereof, said outer sleeve serving as a guide tube for said member,

d. said part supported in said housing comprising a able member and in abutting relation with said element means,

e. a helical compression spring disposed axially within said outer sleeve between said inner sleeve and said movable member to return the latter to its outer position upon release of said push button,

. the surface portion of said part in the path of movement of said striking means which obstructs movement thereof comprising the end edge of said inner sleeve nearer to said movable member, and

g. the passageway through said inner sleeve defining at least apart of the path of movement of said striking means toward said element means after being moved out of engagement with the end edge of said.

inner sleeve nearer to said movable member by movement of said part of said movable member against said striking means. 

1. A push button piezoelectric lighter comprising, in combination, a. electrode means forming a spark gap, b. a housing, c. piezoelectric element means disposed within said housing, said element means being electrically connected in circuit with said electrode means, d. a member movable in said housing between outer and inner positions, said member including a push button accessible exteriorly of said housing for manually imparting movement thereto from its outer position toward its inner position, e. striking means comprising a hammer for imparting a hammer blow upon said element means, f. elongated compressible spring means to effect movement of said striking means in a path of movement toward said element means, said spring means being compressible from an inactive position to an active position by movement of said member from its outer to its inner position, the rear end portion of said spring means being anchored to said movable member, said striking means being movably carried within said housing at the forward end portion of said spring means, g. the forward end portion of said spring means being bent to hold said striking means in a position laterally displaced with respect to the center line of said spring means at the rear end portion thereof, h. a part supported in said housing between said element means and said movable member, said part having a surface portion in the path of movement of said striking means which obstructs movement and provides a support against which said striking means initially rests in its path of movement toward said element means when said spring means is being compressed from its inactive to its active position, and i. means for moving said striking means at the forward end portion of said spring means toward the center line of the rear portion of said spring means and out of engagement with said surface portion when said spring means is compressed and in its active position, said striking means upon movement out of engagement with said surface portion being free to move in its path of movement toward said piezoelectric element means to impart a hammer blow thereto to generate a voltage and to spark across said gap, j. said means for moving said striking means out of engagement with said surface portion comprising a part of said movable member facing said striking means which is shaped to effect such movement of said striking means with movement of said member against said striking means.
 2. A push button piezoelectric lighter as set forth in claim 5 in which a. said movable member is axially recessed, said recess defining a bore extending from the inner end toward the outer push button end of said member, b. said elongated spring means comprising a helical coil spring, the rear end portion of said coil spring being frictionally held in said bore to anchor said coil spring to said movable member, and c. said bore at the inner open end thereof being of conical form and enlarged and providing a surface which defines said part of said movable member facing said striking means, d. said enlarged open end of said bore, with movement of said member against said striking means, clutching the latter to move said striking means out of engagement with said surface portion.
 3. A push button piezoelectric lighter as set forth in claim 6 in which a. said striking means comprises a rear plug-shaped part and a front striking head part serving as said hammer, b. said striking head part being of larger cross-sectional area than said plug-shaped part, and c. said plug-shaped part extending within the front end portion of said coil spring.
 4. A push button piezoelectric lighter as set forth in claim 5 in which (a) said housing comprises an elongated hollow outer sleeve, b. said piezoelectric element means being disposed within said housing at one end thereof, c. said movable member being disposed within said outer sleeve at the opposite end thereof, said outer sleeve serving as a guide tube for said member, d. said part supported in said housing comprising a hollow inner sleeve disposed within said outer sleeve between said element means and said movable member and in abutting relation with said element means, e. a helical compression spring disposed axially within said outer sleeve between said inner sleeve and said movable member to return the latter to its outer position upon release of said push button, f. the surface portion of said part in the path of movement of said striking means which obstructs movement thereof comprising the end edge of said inner sleeve nearer to said movable member, and g. the passageway through said inner sleeve defining at least a part of the path of movement of said striking means toward said element means after being moved out of engagement with the end edge of said inner sleeve nearer to said movable member by movement of said part of said moVable member against said striking means. 